Tim McJilton Tim McJilton - 4 months ago 15
Python Question

How often does python flush to a file?


  1. How often does Python flush to a file?

  2. How often does Python flush to stdout?



I'm unsure about (1).

As for (2), I believe Python flushes to stdout after every new line. But, if you overload stdout to be to a file, does it flush as often?

Answer

For file operations, Python uses the operating system's default buffering unless you configure it do otherwise. You can specify a buffer size, unbuffered, or line buffered.

For example, the open function takes a buffer size argument.

http://docs.python.org/library/functions.html#open

"The optional buffering argument specifies the file’s desired buffer size: 0 means unbuffered, 1 means line buffered, any other positive value means use a buffer of (approximately) that size. A negative buffering means to use the system default, which is usually line buffered for tty devices and fully buffered for other files. If omitted, the system default is used."

bufsize = 0
f = open('file.txt', 'w', bufsize)